Lab Stuff Flashcards
Sensitivity
true positive rate (%)
(sensitivity = 1-false negative rate)
If test has low sensitivity, false negatives will occur more
Specificity
true negative rate (%)
(specificity = 1 - false positive rate)
If a test has low specificty, false positive results will be more frequent
Testing during the window period
Produces a false negative reaction
In general, tests w/ higher sensitivity will have a shorter winderow period
Kinetics of antibody appearance
When does IgM first appear in serum
4-5 days post infection
Pathogen IgM cleared ~6 mo, post infection
When does IgG first appear in serum
~1 week post infection
How to Dx pathogen serologically
IgM w/ current infection
4-fold or greater increase in IgG titer in serial serum samples taken at least two weeks apart
Lateral flow antigen capture assays
mAbs that are specific for viral antigens are attached to a plastic strip
Pt samples are added to saline, deposited into a well, and flow across the test strip by capillary action
Antigen will be captured by mAb
Lateral flow antigen capture ELISA for SARs-CoV-2
Highly sensitive = Low false (+) rate
Highly specific = Low false (-) rate
and vice versa
A. High sensitivity
Better to have false (+) in this case than false (-)
Restriction Fragment Length polymorphism
Can be used to compare the genome sequences of closely related species or those invidividuals within a particular species
in situ hybridization test
Pathogen RNA/DNA in patient tissue/cell samples is detected by hybridization to a complimentary enzyme- or fluorescent-labeled, ss oligonucleotide probe
NAAT
Nucleic Acid Amplification Test:
PCR
RT-PCR
Isothermal amplification (can be used to detect RNA)
RNA cannot be used as a template for PCR
lymphocyte proliferation assay
The lymphocyte proliferation assay uses incorporation of radioactive nucleotides into the DNA of dividing cells as a way to determine if T cells can respond to stimuli.
